Optical recording medium having a pre-formed recording track which is offset along its width to record frame sync signals of information

Abstract

In an optical recording medium on which the main information is recorded on a pre-formed recording track along the track direction and in which the recorded data are read out by optical means, frame sync signals based on the same format as the format for the main information are pre-recorded by offsetting the recording track itself along its width for each frame as an information recording unit, for facilitating frame synchronization and simplifying the construction through the use of a sole common synchronizing circuit. The information pre-recorded by offsetting the track itself along its width includes not only the frame sync signals but also any reproduce-only information for increasing the disc recording capacity. The reproducing circuit for reproducing the frame sync signals of the main information recorded along the track direction of the recording track, and the reproducing circuit for reproducing the frame sync signals having the same format as the main information among the information recorded by offsetting the track along its width, are formed as a common circuit for simplifying the circuit construction.

What is claimed is: 
     
       1. A magneto-optical recording medium for recording main information data which are organized into a sequence of a predetermined number of frames, each frame, prior to recording, having a frame sync signal located at a particular point in the frame, the optical recording medium comprising: a recording track extending in a track direction;   a recordable region for magneto-optically recording the main information on the recording track along the track direction; and   wherein for each recorded frame of main information, frame sync signals having the same signal format as that of the frame sync signals for the main information data are previously recorded by offsetting the recording track in a direction perpendicular to the track direction.   
     
     
       2. The optical recording medium according to claim 1, wherein the recording track is offset perpendicular to the track direction to record reproduce-only information having the same frame sync signal format as the frame sync signal format of the main information data. 
     
     
       3. A magneto-optical recording medium having a magneto-optical recording surface and comprising: a recording track extending in a track direction in the magneto-optical recording surface, the magneto-optical recording surface along the track being magneto-optically altered to record main information data organized into a sequence of frames; and   wherein for each recorded frame of main information data, a separate frame sync signal is previously recorded by offsetting the recording track in a direction perpendicular to the track direction at a predetermined location along the track relative to such recorded frame of main information data.   
     
     
       4. A magneto-optical recording medium according to claim 3 wherein the previously recorded frame sync signal is located at the leading end of each frame of recorded main information data. 
     
     
       5. A magneto-optical recording medium according to claim 4 wherein the recorded main information data is organized according to a conventional Compact Disc (CD) format having 98 frames of data, each frame of data having 588T of main information data, where T represents a channel clock period, and each previously recorded frame sync signal includes two, sequential track offset portions, each offset portion having a length corresponding to 11T. 
     
     
       6. A magneto-optical recording medium according to claim 4 wherein the recorded main information data is organized according to a conventional Compact Disc (CD) format having 98 frames of data, each frame of data having 588T of main information data, where T represents a channel clock period, and each previously recorded frame sync signal includes a first track portion offset in a first direction perpendicular to the track direction for a length corresponding to 11T and a second track portion immediately following the first track portion and offset in a second direction, opposite to the first direction and perpendicular to the track direction, for a length corresponding to 11T. 
     
     
       7. An optical recording medium for recording main information data which are organized into a sequence of a predetermined number of frames, each frame, prior to recording, having a frame sync signal located at a particular point in the frame, the optical recording medium comprising: a recording track extending in a track direction;   a recordable region for optically recording the main information without the frame sync signals on the recording track along the track direction; and   wherein for each recorded frame of main information, frame sync signals having the same signal format as that of the frame sync signals for the main information data are previously recorded by offsetting the recording track in a direction perpendicular to the track direction.   
     
     
       8. The optical recording medium according to claim 7, wherein the recording track is offset perpendicular to the track direction to record reproduce-only information having the same frame sync signal format as the frame sync signal format of the main information data. 
     
     
       9. A optical recording medium having a optical recording surface and comprising: a recording track extending in a track direction in the optical recording surface, the optical recording surface along the track being optically altered to record main information data organized-into a sequence of frames; and   wherein for each recorded frame of main information data, a separate frame sync signal is previously recorded by offsetting the recording track in a direction perpendicular to the track direction at a predetermined location along the track relative to such recorded frame of main information data.   
     
     
       10. A optical recording medium according to claim 9 wherein the previously recorded frame sync signal is located at the leading end of each frame of recorded main information data. 
     
     
       11. A optical recording medium according to claim 10 wherein the recorded main information data is organized according to a conventional Compact Disc (CD) format having 98 frames of data, each frame of data having 588T of main information data, where T represents a channel clock period, and the previously recorded frame sync signal includes a first track portion offset in a first direction perpendicular to the track direction for a length corresponding to 11T and a second track portion immediately following the first track portion and offset in a second direction, opposite to the first direction and perpendicular to the track direction, for a length corresponding to 11T. 
     
     
       12. A magneto-optical recording medium for recording main information data organized according to a conventional Compact Disc (CD) format having 98 frames of data, each frame of data having 588T of main information data, where T represents a channel clock period, and comprising: a recording track extending in a track direction;   a recordable region for magneto-optically recording the main information on the recording track along the track direction; and   wherein frame sync signals having the same signal format as that of the frame sync signals for the main information data are previously recorded, each previously recorded frame sync signal including a first track portion offset in a first direction perpendicular to the track direction for a length corresponding to 11T and a second track portion immediately following the first track portion and offset in a second direction, opposite to the first direction and perpendicular to the track direction, for a length corresponding to 11T.